Welcome to the second edition of our book on SSH, one of the world’s most popular approaches to computer network security. Here’s a sampling of what’s new in this edition:
Over 100 new features, options, and configuration keywords from the latest versions of OpenSSH and SSH Tectia (formerly known as SSH Secure Shell or SSH2 from ssh.com)
Expanded material on the SSH-2 protocol and its internals, including a step-by-step tour through the transport, authentication, and connection phases
Running OpenSSH on Microsoft Windows and Macintosh OS X
All-new chapters on Windows software such as Tectia, SecureCRT, and PuTTY
Scalable authentication techniques for large installations, including X.509 certificates
Single sign-on between Linux and Windows via Kerberos/GSSAPI
Logging and debugging in greater depth
Tectia’s metaconfiguration, subconfiguration, and plugins, with examples
...and much more! You might be surprised at how much is changed, but in the past four years, SSH has significantly evolved:
- SSH-2 protocol triumphant
Back in 2001, only a handful of SSH products supported the relatively new SSH-2 protocol, and the primary implementation was commercial. Today, the old SSH-1 protocol is dying out and all modern SSH products, free and commercial, use the more secure and flexible SSH-2 protocol. We now recommend that everyone avoid SSH-1.
- The rise of OpenSSH
This little upstart from the OpenBSD world has become the dominant implementation of SSH on the Internet, snatching the crown from the original, SSH Secure Shell (now called SSH Tectia, which we abbreviate as Tectia). Tectia is still more powerful than OpenSSH in important ways; but as OpenSSH is now included as standard with Linux, Solaris, Mac OS X, and beyond, it dominates in pure numbers.
- The death of telnet and the r-tools
The insecure programs telnet, rsh, rcp, and rlogin--long the standards for communication between computers—are effectively extinct.[1] FTP is also on the way out, except when operated behind firewalls or over private lines.
- An explosion of Windows products
In 2001, there were a handful of SSH implementations for Windows; now there are dozens of GUI clients and several robust servers, not to mention a full port of the free OpenSSH.
- Increased attacks
The Internet has experienced a sharp rise in computer intrusions. Now more than ever, your servers and firewalls should be configured to block all remote accesses except via SSH (or other secure protocols).
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